import { Directive, Input, ElementRef, NgZone, OnChanges, SimpleChanges } from '@angular/core';
import { NavigationExtras } from '@angular/router';
import { ActivatedRoute, Router, UrlTree } from '@angular/router';
import { NavigationTransition } from '@nativescript/core';
import { NativeScriptDebug } from '../trace';
import { RouterExtensions } from './router-extensions';
import { NavigationOptions } from './ns-location-utils';
import { Subject } from 'rxjs';

// Copied from "@angular/router/src/config"
export type QueryParamsHandling = 'merge' | 'preserve' | '';

/**
 * The nsRouterLink directive lets you link to specific parts of your app.
 *
 * Consider the following route configuration:
 * ```
 * [{ path: "/user", component: UserCmp }]
 * ```
 *
 * When linking to this `User` route, you can write:
 *
 * ```
 * <a [nsRouterLink]="["/user"]">link to user component</a>
 * ```
 *
 * NSRouterLink expects the value to be an array of path segments, followed by the params
 * for that level of routing. For instance `["/team", {teamId: 1}, "user", {userId: 2}]`
 * means that we want to generate a link to `/team;teamId=1/user;userId=2`.
 *
 * The first segment name can be prepended with `/`, `./`, or `../`.
 * If the segment begins with `/`, the router will look up the route from the root of the app.
 * If the segment begins with `./`, or doesn"t begin with a slash, the router will
 * instead look in the current component"s children for the route.
 * And if the segment begins with `../`, the router will go up one level.
 */
@Directive({ selector: '[nsRouterLink]' })
export class NSRouterLink implements OnChanges {
	// tslint:disable-line:directive-class-suffix
	@Input() target: string;
	@Input() queryParams: { [k: string]: any };
	@Input() fragment: string;

	@Input() queryParamsHandling: QueryParamsHandling;
	@Input() preserveQueryParams: boolean;
	@Input() preserveFragment: boolean;
	@Input() skipLocationChange: boolean;
	@Input() replaceUrl: boolean;

	@Input() clearHistory: boolean;
	@Input() pageTransition: boolean | string | NavigationTransition = true;
	@Input() pageTransitionDuration;

	/** @internal */
	onChanges = new Subject<NSRouterLink>();

	private commands: any[] = [];

	constructor(private ngZone: NgZone, private router: Router, private navigator: RouterExtensions, private route: ActivatedRoute, private el: ElementRef) {}

	ngAfterViewInit() {
		this.el.nativeElement.on('tap', () => {
			this.ngZone.run(() => {
				if (NativeScriptDebug.isLogEnabled()) {
					NativeScriptDebug.routerLog(`nsRouterLink.tapped: ${this.commands} ` + `clear: ${this.clearHistory} ` + `transition: ${JSON.stringify(this.pageTransition)} ` + `duration: ${this.pageTransitionDuration}`);
				}

				const extras = this.getExtras();
				// this.navigator.navigateByUrl(this.urlTree, extras);
				this.navigator.navigate(this.commands, {
					...extras,
					relativeTo: this.route,
					queryParams: this.queryParams,
					fragment: this.fragment,
					queryParamsHandling: this.queryParamsHandling,
					preserveFragment: attrBoolValue(this.preserveFragment),
				});
			});
		});
	}

	ngOnChanges(changes: SimpleChanges) {
		// This is subscribed to by `RouterLinkActive` so that it knows to update when there are changes
		// to the RouterLinks it's tracking.
		this.onChanges.next(this);
	}

	@Input('nsRouterLink')
	set params(data: any[] | string) {
		if (Array.isArray(data)) {
			this.commands = data;
		} else {
			this.commands = [data];
		}
	}

	private getExtras(): NavigationExtras & NavigationOptions {
		const transition = this.getTransition();
		return {
			skipLocationChange: attrBoolValue(this.skipLocationChange),
			replaceUrl: attrBoolValue(this.replaceUrl),

			clearHistory: this.convertClearHistory(this.clearHistory),
			animated: transition.animated,
			transition: transition.transition,
		};
	}

	get urlTree(): UrlTree {
		const urlTree = this.router.createUrlTree(this.commands, {
			relativeTo: this.route,
			queryParams: this.queryParams,
			fragment: this.fragment,
			queryParamsHandling: this.queryParamsHandling,
			preserveFragment: attrBoolValue(this.preserveFragment),
		});

		if (NativeScriptDebug.isLogEnabled()) {
			NativeScriptDebug.routerLog(`nsRouterLink urlTree created: ${urlTree}`);
		}

		return urlTree;
	}

	private convertClearHistory(value: boolean | string): boolean {
		return value === true || value === 'true';
	}

	private getTransition(): { animated: boolean; transition?: NavigationTransition } {
		let transition: NavigationTransition;
		let animated: boolean;

		if (typeof this.pageTransition === 'boolean') {
			animated = this.pageTransition;
		} else if (typeof this.pageTransition === 'string') {
			if (this.pageTransition === 'none' || this.pageTransition === 'false') {
				animated = false;
			} else {
				animated = true;
				transition = {
					name: <string>this.pageTransition,
				};
			}
		} else {
			animated = true;
			transition = <NavigationTransition>this.pageTransition;
		}

		let duration = +this.pageTransitionDuration;
		if (!isNaN(duration)) {
			transition = transition || {};
			transition.duration = duration;
		}

		return { animated, transition };
	}
}

function attrBoolValue(s: any): boolean {
	return s === '' || !!s;
}
